Outdoor swimming pools are being associated more and more frequently with protective covers and/or shelters. These elements make it possible to keep the pool clean by reducing dirt and grime from the outside, and they also contribute to making swimming pools safer, shelters having the added advantage of increasing the duration of the bathing season.
Conventionally, covers and the transparent surfaces of shelters are treated so as to filter out ultraviolet rays. The Applicant has found that variation in the amount of ultraviolet rays reaching the water of a swimming pool strongly influences the rate at which halogens such as chlorine and bromine disappear.
As a general rule, doses of chlorine or bromine are calculated depending on the characteristics of the swimming pool when said swimming pool is not covered. When the swimming pool is covered, the rate at which the chlorine and bromine disappear is considerably slowed down and consequently, due to lack of regulation in real time, the concentration increases rapidly and becomes too high. That concentration that is too high is detrimental because it makes the water aggressive to the skin and to the liner of the pool. Another drawback is that the lack of regulation leads to too much disinfectant being consumed.
A regulating device is available on the market for measuring, in real time, the concentration of halogenated disinfectant. However, that device uses a probe based on the redox effect and is not satisfactory. Measurement of redox potential is not reliable in view of many external factors interfering with such measurements. Moreover, the device deduces that chlorine or bromine are absent if there is no electrolysis, yet such absence of electrolysis may be due to a low microbe presence in the water being analyzed. In that event, the device causes a new dose of disinfectant to be added, even though the concentration of disinfectant may be greater than the required maximum concentration.
A device has also been proposed for measuring concentrations of chlorine, in real time, by using a reagent that reacts in the presence of chlorine, said reagent being associated with a colorimetric detector. However, that device is not reliable in the sense that the reagent is bleached when the concentration of chlorine exceeds a certain limit, thus distorting the measurement. In contrast, the device is unable to distinguish between an absence of reagent in the mixture and a concentration of chlorine that is low, and therefore it can cause chlorine to be added when the concentration of chlorine is sufficient or even greater than the required maximum concentration.